Advice on selecting parts for a city commuter

[vovalos]

Hello all,
I would like to build my first e-bike sometime soon and I'm having a hard time navigating the lack of official information (i.e. from manufacturers) and the tons of (oftent conflicting) user information on various forums. It seems like the majority of DIY enthusiasts are building bikes for off road, so it's hard to gauge whether the info would be applicable to me.

I'm building city commuter to do about 40km on paved roads with some hills, but nothing major (biggest grade I have is 6%) and building it to supplement pedaling rather than take over. I can pedal the route with an average speed of ~20km/h and I would like to push it to average over 30 with flat stretches at 40km/h. My legal limit is 500W, but considering my conditions I won't need more anyway. I'm a big guy, at close to 100kg and I ride a large framed Norco hybrid with 700cc wheels.

Here are my questions:
1. I have shocks on my front fork. From what I can gather, it would be a bad idea to put a hub drive there. Is this right? or at my relatively low power this won't be an issue yet?
2. I keep reading that mid-drives are more expensive than hubs. I've looked at the BSS02 and I can get it with a 11.6Ah battery for 850$ from amazon, even cheaper if I buy from china. When I looked at hub kits from Grin (ebikes.ca), I'm very quickly at 1000$+. The reason I'm looking at Grin is that I would put a torque sensor if I have the opportunity. So is Grin just comparatively expensive?
2a. Are there other controllers apart form CA3 that would allow using a torque sensor?
2b. What are the hub motors that would fit my needs? Which models would be considered reliable?
2c. What are good stores/websites to buy a kit? (I'm in Canada)
3. There are also very mixed feeling about torque sensors. I've read many posts saying they lack reliability. Are there good models?
4. Another option I considered is the middrive by Tongsheng - TSDZ2. It offers a built in torque sensor, but from what I can gather suffers from reliability problems. Did anyone have experience with this motor, what's your opinion?
5. Side question I have V brakes, which have never been insufficient. Should I be upgrading to disk? Is it hard to do?

Thanks in advance for your input.

 

[Dewey]

I have limited experience with hub motors, I fitted a hill Topper kit but returned it after a week and went with a Bafang mid drive, there are other site contributors with more experience better qualified to comment, but your wants sound reasonable. A hub motor adds maybe 10-15lb to a fork depending on if you go with a lighter geared hub motor or a direct drive, I can’t see why either wouldn’t work with a suspension fork but as you are riding on pavement you could go with a rigid fork to save weight and at the same time get a replacement with the necessary mounting points for disk brake, you could just put a disk on the front and keep the v brake on the rear. Grin is the best, but another Canadian supplier of hub motors would be Golden Motor Canada. The bottom bracket torque sensors by Grin work with their CA system, unsure if they work with others, and you drill a hole into your bottom bracket shell for a wire, some measure torque on only one side/crank (see this), the Sempu torque sensors Grin sells seem good value and unlike the Thun and TDCM sensors the Sempu fits a variety of different bb shell widths. A review of the tsdz2 motor is https://www.electricbike.com/tsdz2-750w-mid-drive-torque-sensing/

 

[vovalos]

Thanks Dewey. I've read the Grin website up and down at this point, will look into Golden motor site. The TSDZ review was pretty useful too, but the review + comments just confirm that it may not be as reliable/well built as I would like it to be.

Anyone have any comments on Cycle analyst vs default Bafang computers?

 

[harryS]

This is a 500W geared motor from ebay/amazon vendor ebikeling. It's not too heavy at 9 pounds w/o freewheel or the rubber.He sells the same motor for front wheel applications. I'm 200 pounds, and it will drive my bike up around 20 mph ( 30 km/hour) on 36V. I'v got two kit bikes running this motor. I have a 3rd motor spoked into a 26" fatbike rim for the frint wheel that I only used a few times one winter to try out 2WD. WHile it tops out at 20 mph, it's probably best ridden between 12-16 mph,

These kits used to only cost about $170 on ebay. You just get a 3 level PAS running off a cadence sensor, plus an LED display. I add a $7 bike computer for speedometer/odometer. If I want to play scientist, I can hook up one of my $12 wattmeters and measure power out of battery when riding or into battery when charging.

I didn't think I would get much more spending $150 just for the Cycle Analyst. After a few rides, I already know how much power the controller can output and get a feel for the range on a battery.

Pics of the two bikes using this motor. The first one is using a $280 36V9AH dolphin pack I bought in 2015. Last year, I ran it over 50 miles at 13 mph. Then I got another 10 miles limping along at 10 mph.



I did a Bafang BBS02 in 2016. At the time I wanted a rack battery, but that's openly ebike. I prefer staying under the radar today. I paid close to $1100 for the motor and battery. Today, I think your $850 is possible.It's fast and quiet.



It's not hard to install a BBS02. There's less parts (no controller) to locate, and the wiring is sleek plug/play cables. Most hub motor cabling is a rats nest.

The pedal assist on a BBS02 needs to be set at 9 levels, and even then, it's still crude. Some owners have adjusted the start currents with the programming cable to get a better pedal feel. New BBS02 kits won't allow you to feather in throttle while using pedal assist. You either have to install a simple fix (to an EE like me, it's simple) or use them separately.

I built one front drive bike. Installed two torque arms. It's only a 300W motor so there's probably little risk. If I were only bulding one ebike, I'd always go rear wheel. Unless you have an expensive internal gear hub you want to keep, the added complexity is minimal, and the safety factor really goes in your favor, plus you can go with more watts if you wish.

The ebikeling controllers don't have good cadence control, but the 3 level system shuts PAS 1 off around 12 mph. If I ride at 13 mph, which is my natural speed, the motor and I share the load and the pedal feel is fine. Other controllers, like the KT series, have a PAS system that feels natural to me. I've built some other hubmotor bikes using those controllers.

 

[Dewey]

Thanks Dewey. I've read the Grin website up and down at this point, will look into Golden motor site. The TSDZ review was pretty useful too, but the review + comments just confirm that it may not be as reliable/well built as I would like it to be.

Anyone have any comments on Cycle analyst vs default Bafang computers?

It is a learning curve, try also looking at Micah Toll’s ebike school website, and ask your questions on the electricbike.com and Endless Sphere forums. There are more suppliers listed on the Reddit ebikes wiki https://www.reddit.com/r/ebikes/wiki/index. I suggest you avoid Bionx as the company has gone bust and parts support will run out.